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The head of the light has a slightly scalloped aluminum bezel ring and some shallow cooling fins. The silver magnetic selector ring has some rounded grooves which help in the rotation of the ring. The light has 3 holes on the tailcap ring for lanyard attachment. but there is no tailcap switch.
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The light has knurling with deep grooves along the battery tube which are located where the hand would be placed. The XTAR logo & character are bright and clear.
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The light has 3 parts(i.e, head, battery tube, and tailcap). Tail threads are anodized at the battery tube & tailcap regions, so you can unscrew it a little for lock-out.
There is a large & round positive contact surface which has a reverse polarity protection function in the head. The 3 flat negative terminal contact discs at the tailcap look unique and solid.
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Changing the mode is very easy and can be quickly accomplished by rotating the magnetic ring right and left with one hand. The S1 has a large head and uses three cool white XM-L U2 emitters, each well-centered in their own deep and smooth reflector well. The wells overlap slightly, but each reflector is quite deep(~5.5cm) overall, so I would expect good throw of beam.
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The battery tube at head side is a circle, but the inside of the battery tube at tailcap side is bored in a triangular pattern which allows three 18650 batteries to slot into and to make them steady.
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Screw threads on the battery tube are fine triangular-cut and quite smooth with no cross-threading or squeaking. The thinnest part of the battery tube is 2mm thick.
[Correction-2012.01.13] Screw threads are fine rectangular-cut. Screw thread pitch is very fine and groove is somewhat deep. I've gotten farsighted several years ago. Sorry!
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[Edit] : The followings are added(2012.01.12).
The flat negative terminal contact discs on the inside of the tailcap which can rotate on center axis are high elasticity spring structure. Once they are inserted into the battery tube, the tailcap only can be rotated.
The light can tailstand perfectly. There are 3 small holes machined into the tailcap ring for lanyard or split-ring attachment. The light doesn't roll well due to the tailcap ring. While the light is bigger than I expected overall, construction feels very solid and reliable. Overall build quality is excellent.
.User InterfaceOn-off and mode switching is controlled entirely by the silver magnetic selector ring in the head(i.e, there is no clicky on-off switch).
The six selector ring levels on the light are SOS - Strobe - High - Off ("O")- Preset - Select, arranged clockwise.
When the "▲" symbol on the selector ring is set to "O" position, the light is off or on standby.
You can select SOS, Strobe, and High mode by rotating the selector ring to the left. Also you can select Preset mode by rotating it to the right. The preset mode is user-defined brightness at a certain level. When rotating the "▲" symbol on the selector ring to "Select" position, the light output will begin to ramp up and down, starting from the current preset output level. To select the output level you want, simply rotate the "▲" symbol on the selector ring quickly back to the "Preset" position. Once an output level is selected, that level is memorized.

All modes switching is controlled by the magnetic selector ring in the head without clicky on-off switch on the tailcap, a standby(parasitic) current is being drawn. It's less than 5mA manufacturer claims. If it's a problem, you can use tailcap lock-out function easily.
Although not very easy, you can switch back and forth one-handed.(You can do that with very ease when you put the gloves.)
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The left & right are the button-top protected 18650's & flat-top unprotected 18650's respectively. I can't turn the light on with my flat-top unprotected 18650 cells, but the button-top protected cells have no problem. If you attach a tiny neodymium magnet(NdFeB) on the flat-top cells, the problem is solved.
Neither of this issue affect practical usage though, but I hope XTAR would consider and solve this issue.

The S1 has nice battery flexibility by running the three wells in parallel, so you can use 1 or 2x18650 cells in unavoidable emergency. But I'd say you can use 1 or 2xcells only in emergency. I'd recommend you use the batteries of same types, same brands, same charging levels, same capacity(more than 2600mAh at least), and don't mix batteries of old & new. Also note CR123A's or RCR123's are banned.
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The S1 is not an EDC but a big light.
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From left to right, VicLite 18650, Solarforce L2T, Skihunt Defier X3, XTAR S1, XTAR TZ-50, Sky Ray STL-V2.
.The net weight is 882g and 1kg including 18650 batteries..PWMS1 is a PWM controlled light. I can see flickering at low & med. level, but can't see it visually in practical use. There's no sign of PWM at high mode.I notice that there is very little buzzing sound on the preset mode and select mode when holding the light close to my ear to hear it.
.[Edit] : The followings are added(2012.01.13).RuntimeThe runtime for 50% output of high & med. level on 3xPanasonic unprotected 18650(3100mAh)'s is appr. 81 & 158 mins respectively in my test. The S1 provides good runtime, but it's a shame that it doesn't provide steady or flat regulation. It doesn't behave consistency on both levels as the batteries run down. I stop running the light to protect the batteries from overdischarge in 100mins & 179mins respectively.

The voltage of the battery at the start and end of the test is as follows.
1) High Mode
Cell-1 : 4.18V --> 3.19V
Cell-2 : 4.18V --> 3.18V
Cell-3 : 4.18V --> 3.17V

The max. surface temperatures of the upper point(bezel ring) & lower point(lower fin) are 46℃, and 48℃ respectively. Also 43℃ on battery tube.
In my view, the heat is not a problem on the S1 for 20mins continuous running on high level.
.Beamshot1) White door beamshot (about 60cm from the white door)

The beam profile produces a small sized hotspot with a soft corona tapering into the spill beam. At a close range(i.e.~5m), the spill beam looks like a triangular petal-like pattern. But it is hardly noticeable or is not issue in real life. The beam tint on my sample is very slightly hint of green on hot spot and cool white on side spill.
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2) Indoor beamshot (about 7m from the target)

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3) Outdoor beamshot (about 55m from the target)

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4) Outdoor beamshot (about 60~65m from the target)

.5) Outdoor beamshot (far more than 130m from the target)

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[Edit] : The following added(2012.01.14).Peak Throw & Beam Distance
I got 54,300 lux of peak throw at 1m and 466m of beam distance(to 0.25lux).[Edit] : I measured 56,100 lux at 1m, with full charged NCR18650As, is based on 30 secs after activation which translates into an ANSI FL-1 beam distance of 473m. (2012.04.21)
.[Edit] : Ramp added(2012.01.18).
The ramp of S1 is 7 sec from min. to max. brightness, totally 14 sec cycle as shown in the above graph..
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.Thanks for reading the review.

* S1 provided by TorchGear for review.

[ Note (12.04.22) : You can find the Xtar S1 comparison review-test version & final version here or in the #22'nd reply down there. ]

Nice! I'm liking this light. I know it says IPX-8 waterproof, but do you know if it's good down to 10 feet or something? I hear that some IPX-8 lights actually leak when placed underwater, and others hold up well (Fenix).

CyberCT, this light did about 39 deg C measured at the bezel after 12 mins run on the highest mode. Ambient was 29 deg C. This is like the absolute opposite of Nitecore TM11.

I have also done a review on it but it's slightly different and is very measurement based. Also compared via photos to the Olight M3X and Fenix TK70. Just do a google on it, it will turn up. I can't link it here.

The light uses 475Hz PWM, not current controlled. I figured that it is best not to sugar-coat any reviews because folks will buy it and a hoo-haa later is worse. 475Hz is actually not too bad and usable in real life, it's about 3X faster than budget lights from Ultrafire/Trustfire/Sky Ray. But i guess if you are that type who is super sensitive to even 4kHz PWM which is still very slightly visible on a fan and in the shower (!!) then you might not want this light.

So it depends on your priorities. It gets pretty close to TK70's performance, very efficient driver (it runs parallel and takes about 6.5A at the tail for 2100L OTF!) and most importantly at least for me, a form factor that is much usable than the TK70. MY TK70 is in 3D mode with 2 x 32600, still a bit unwieldy when i hold both in my hand and shine it around. This is much more solid in feel than the TK70, which i believe most would think it's already very solid.

CyberCT, this light did about 39 deg C measured at the bezel after 12 mins run on the highest mode. Ambient was 29 deg C. This is like the absolute opposite of Nitecore TM11.

I have also done a review on it but it's slightly different and is very measurement based. Also compared via photos to the Olight M3X and Fenix TK70. Just do a google on it, it will turn up. I can't link it here.

The light uses 475Hz PWM, not current controlled. I figured that it is best not to sugar-coat any reviews because folks will buy it and a hoo-haa later is worse. 475Hz is actually not too bad and usable in real life, it's about 3X faster than budget lights from Ultrafire/Trustfire/Sky Ray. But i guess if you are that type who is super sensitive to even 4kHz PWM which is still visible on a fan and in the shower (!!) then you might not want this light.

So it depends on your priorities. It gets pretty close to TK70's performance, very efficient (about 6.5A at the tail for 2100L OTF!) and most importantly at least for me, a form factor that is much usable than the TK70. MY TK70 is in 3D mode with 2 x 32600, still a bit unwieldy when i hold both in my hand and shine it around. This is much more solid in feel than the TK70, which i believe most would think it's already very solid.

well said, 2100. I love how the light looks though! If you manage to persuade Xtar to drop PWM, I'd happily get one!

Nice! I'm liking this light. I know it says IPX-8 waterproof, but do you know if it's good down to 10 feet or something? I hear that some IPX-8 lights actually leak when placed underwater, and others hold up well (Fenix).

How hot does it get on the highest mode?

Sorry, I'm not sure if S1 is good down to the depth you mention yet. According to my heat measurement, S1 reached 48 degrees C surface temperature in 24 mins without cooling.
You can see the related result soon.

Originally Posted by Mr. Tone

This looks like a great light. I really like the form factor. Are the LED's easily accesible so one could mod it to neutral white?

Thanks. As far as I know Xtar as never offered neutral white lights from the factory, at least I haven't seen any. I really like the parallel battery configuration. The shorter, fatter design seems better than the super long skinny type which are so common. I have a Thrunite Catapult V3 and it honestly could have a handle diameter closer to that of a 2D maglite for my tastes and it is thicker than most other 2x18650 lights. You have to hold that light close to the head to find a good balance.

Thanks. As far as I know Xtar as never offered neutral white lights from the factory, at least I haven't seen any. I really like the parallel battery configuration. The shorter, fatter design seems better than the super long skinny type which are so common. I have a Thrunite Catapult V3 and it honestly could have a handle diameter closer to that of a 2D maglite for my tastes and it is thicker than most other 2x18650 lights. You have to hold that light close to the head to find a good balance.

I think S1 has a better balance of the weight between head and body(battery tube+tailcap) than common 2x18650 light.

I've checked the head and found the LED's easily accessible, so you can mod it to neutral white as you want. The bezel ring can be opend by unscrewing it without any tool.

good review. interesting light, just a shame about the lack of regulation on high

It's actually regulated. Look at the first 20 mins and then 60 mins. The light reaches nearly 50 deg C by the 24th minute (which is very very good, in fact the best of my multi-XML lights even better than the TK70). The light tries to suck ~ 2.2A from each cell. Seriously your eyes cannot tell the diff between 100% and 80%. 100% and 70% is also barely noticeable unless you A-B it directly. For the first 60 mins i am sure everybody would be very happy.

The PWM too, it is very usable in reality. But i do know there are a couple who don't even want kHz range PWM and I do respect that. Perfection comes at a price though.

XTAR S1 Comparison Review - Test Version & Final Version

XTAR has officially released S1-final version. They revised S1-test version according to the reviews comments and suggestions. (I did a review on the test version.)
The S1 final version comes in a sturdy cardboard box, with built-in packing foam and closing flap.
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The final version is sturdy and imposing even just at a glance.
Lst's see how much the final version has changed from the test version of S1 in detail.
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Test version is on the left in the picture and final version on the right. (will be continued in the same order as above.)
They look the same on the surface.
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The external features that have changed on the head are fluted ridges along the bezel ring, and the lower ring which supports a silver magnetic selector ring.
One other change is the rounded groove shape on the selector ring. Thanks to its change, I can switch back and forth one-handed with ease.
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The knurling on the battery tube is less aggressive, but the overall grip is certainly reasonable.
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I can't open the bezel ring on the final version, it seems to be bonded with strong adhesive. The final version has a toughened AR coating lens, while test version a toughtened lens.
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The tiny groove on the positive contact plate is removed and the positive contact block is increased in length. The final version is not different in its 6 labeled modes on the head of the light (i.e. SOS - Strobe - High - Off("O") - Preset - Select, Arranged clockwise). The test version's selector ring continues to turn past all the output modes in either direction. But XTAR prevent the ring from turning to the rigion where there is no output mode, and reduce the total traverse of the ring to 1/2 circumference of the final version.

The battery tube length is reduced a little. Screw threads are anodized for tailcap lockout as the test version was.
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The threads toward the head are square cut, but there is a decreasing in the number of the threads from 7 to 5.
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The threads toward the tailcap are anodized square cut. There is no change in the number of threads.
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The thinnest part of the battery tube is 2 mm thick. The light is definitely one of the most solid lights I've seen.
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The tailcaps are identical and the light can tailstand perfectly. There are 3 small holes machined into the tailcap ring for lanyard or split-ring attachment.[Update - 2012.04.23] The three negative contacts & the base plate on the tailcap rotate much more freely than the positive contact plate on the head as before. [Update - 2012.04.23].[Update - 2012.04.23]

The both tailcaps are fit in each battery tube well, but are not interchangeable between the test & final version.
i.e. The tailcap of the final version fit in the body of the test version and the light just works fine. But the light doesn't work when fitting the tailcap of the test version in the body of the final version. It' is because the height of the base plate on the test version is less than the final version as shown above. I don't mean this is an issue in the final version. This is related to the use of the flat-top cells. [Update - 2012.04.23]

Overall build quality seems excellent.
.User Interface

As before, final version is not different in its UI.
On/off and mode switching is controlled entirely by the silver magnetic selector ring in the head. You can select any mode by rotating the selector ring. The preset mode is user-defined brightness at a certain level. When rotating the "▲" symbol on the selector ring to "Select" position, the light output will begin to ramp up and down in a repeating loop, starting from the current preset output level. To select the output level you want, simply rotate the "▲" symbol on the selector ring quickly back to the "Preset" position. Once an output level is selected, that level is memorized (i.e. will always return to that level unless you start a new Select ramp). The range of the Select mode manufacturer claims is 15~2350 lumens.
.RampThe ramp of the test version is 7 secs from min. to max. output level, totally 14 secs cycle. What this means is that the test version ramp is so quick that you can't select the output level precisely you want. The final version has much longer ramping time for selecting output level (i.e. from 15 lumens to 2350 lumens takes about 22 secs), and there is a 1.5 sec pause at 3%, 25%, 50%, 75%, 98% output level to help the precisely selecting of output level as shown below. The current revision of the ramp is very welcome and nice change according to the user's feedbacks.

But I think the adding a 1~2 secs pause only at those output levels is not a great help me to know what the current output level is. Personally, I don't see the need for 25% and 75% pauses in the ramp. I would like to suggest that XTAR make the light flicker once at 0%, and twice at 50% output, and three times at max.(100%) output to remind users the current output level by keeping 1~2 secs pause at those output levels. This will probably reduce the ramping time to 8 secs (i.e. with 14 secs between min. and max. outputs).
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The flat-top 18650 cells do not work in the test version, but the button-top cells work fine. (If you attach a neodymium magnet(NdFeB) on the flat-top cells in the test version, no problem at all.) Now you can use the flat-top 18650 cells without using a magnet in the final version.
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The final version is not appreciably different in its weight.
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The light comes with a nice pouch instead of a holster.
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I don't think a holster is a good idea for such a big size light, but with a pouch, I can either put the light in my bag without got scratched, or can carry it on my shoulder.
.PWMI can see flickering at lower output level when intentionally waving the light. But I can't see it visually in practical use. There is no sign of PWM at high mode as before. I notice that there is very little buzzing sound on the preset mode amd select mode as before.
.Runtime

The runtime for 50% output of high level on 3xPanasonic unprotected 18650(3100mAh)'s for test & final version are appr. 82 & 75 mins respectively in my test. The test version provides good runtime, while it doesn't provide steady or flat regulation. However the final version does appear to be flatly regulated at high level, while provides less runtime than test version.
The revised final version seems to have a little more output. I stop running the lights to protect the batteries from overdischarge in 89 mins & 104 mins respectively.

The voltage of the battery at the start and end of the test is as follows :
1) Test Version
Cell-1 : 4.18V --> 2.99V
Cell-2 : 4.18V --> 2.96V
Cell-3 : 4.18V --> 3.03V

The beam profile of test & final version produces a small sized hotspot with a soft corona tapering into the spill beam. At a close range(i.e.~5m), the spill beam looks like a triangular petal-like pattern. But it is hardly noticeable or is not issue in real life. The beam tint on test version towards quite cool side of the color spectrum noticeably blue, but the beam tint on final version is close to neutral white perhaps leaning just slightly towards the cool side, but not by much..[Update - 2012.04.22] Indoor beamshot is uploaded.2) Indoor beamshot (about 7m from the target)
2-1) Test version

1) Test version I measured 56,100 lux at 1m, with full charged NCR18650As, is based on 30 secs after activation which translates into an ANSI FL-1 beam distance of 473m.
2) Final versionI measured 60,600 lux at 1m, with full charged NCR18650As, is based on 30 secs after activation which translates into an ANSI FL-1 beam distance of 492m.

The final version seems to have a little more output, resulting in slightly greater throw as well. I think this is due to an improved circuit board to have better regulated output and a toughened AR coating lens.

Re: XTAR S1 Comparison Review - Test Version & Final Version

A lot of the pics in post #22 are red X's... but I ordered an XTAR S1 anyway!

EDIT- I got pics to load..
One observation:

''The tailcaps are identical''
I noticed new tailcap has a deeper step-down into first machined circle, and the middle machined circle is larger in diameter. I also think the little triangular shaped ''feet'' that would be touching ground if tail-standing are a tiny bit larger.

I Love all those macro shots- you can really see all the little machining differences.

Re: XTAR S1 Comparison Review - Test Version & Final Version

You're right and very good at finding the difference between the tailcaps.

I've also updated some notes dated on 12.04.23.

Originally Posted by BWX

A lot of the pics in post #22 are red X's... but I ordered an XTAR S1 anyway!

EDIT- I got pics to load..
One observation:

''The tailcaps are identical''
I noticed new tailcap has a deeper step-down into first machined circle, and the middle machined circle is larger in diameter. I also think the little triangular shaped ''feet'' that would be touching ground if tail-standing are a tiny bit larger.

I Love all those macro shots- you can really see all the little machining differences.

Re: XTAR S1 - Test Version and Final Version Review

At least I have this thread to check out pics while I wait for mine to come in the mail, LOL.

Hey, does the silver magnetic adjustment ring look to be narrower on the final version? I don't mean up and down, but the entire width of the light where the ring is. Might just be photo angles.
The production version is definitely a completely new light. Very similar, but it looks like the body has completely new machining.

Re: XTAR S1 - Test Version and Final Version Review

Originally Posted by BWX

At least I have this thread to check out pics while I wait for mine to come in the mail, LOL.

Hey, does the silver magnetic adjustment ring look to be narrower on the final version? I don't mean up and down, but the entire width of the light where the ring is. Might just be photo angles.
The production version is definitely a completely new light. Very similar, but it looks like the body has completely new machining.

That's a good idea.

I've measured the circumference of the silver magnetic ring on the two lights and both is 22.2cm round. So the diameter is around 7.07cm.
I'm suprised they changed an engine, window, headlamp color, body frame, and accessaries. What else?